Unite said the current pay band for workers failed to reflect the tasks they were being asked to carry out, adding the trust had agreed work for another trust that would mean extra nightly and weekend call outs without consultation.

Unite general secretary Sharon Graham said: ‘Airedale trust's leadership are treating these workers appallingly. Not only are they being underpaid but now the trust expects them to take on out of hours work on top of their already considerable workloads. These workers are absolutely right to strike and they have Unite's complete support.'

The union warned industrial action would intensify if the dispute is not resolved.

Afruj Ruf,  managing director of Integrated Pathology Solutions, said: ‘Our committed staff provide critical, scientific analysis that supports our clinical colleagues and helps patients to get the diagnoses that they need.

‘Every member of staff is appointed to a job description which aligns to national Agenda for Change role profiles and salary bands. We would never change rotas without consultation or without regard to workloads and, whilst we have explored a number of solutions to provide cover for this work, we are not asking our microbiology biomedical scientists to undertake out of hours work for another trust.

‘We regret that we were not able to reach a mutually acceptable agreement with Unite.  However, we have contingency plans in place and will work hard to minimise disruption. 

‘We remain committed to working in partnership with Unite and I hope that we are able to resolve this dispute swiftly.'